Many infants require bottle feeding because they cannot be breastfed, require supplemental nutrition, or due to parental choice. Consequently, many designs and configurations for baby bottles have been invented. Some of the bottles are designed to store baby formula powder and fluid such as water separately so that a need to hand mix baby formula in a challenging environment or a need to refrigerate, then reheat, pre-mixed baby formula is avoided. A baby bottle that stores baby formula powder and fluid such as water separately is convenient and advantageous in many instances. For example it: greatly ameliorates the often challenging and time consuming task of preparing baby formula for consumption when traveling or when outside the home; simplifies supplying infant nutrition at daycare; permits preparation ahead of time for a busy day at or away from home; and greatly reduces the time required to prepare mixed formula. This convenience should also extend to assembling a bottle prior to use and cleaning the bottle after use. In addition, some baby bottles tend to leak if they are tipped over or jostled about in a carrier bag or the like, which can be frustrating and inconvenient.